Because allocating limited resources isn’t in the purview of a 4 year old. As you grow up, you begin to learn who wields the power and resources and how it’s allocated and what the consequences are for those who forgo it or can’t get it.
On a positive note, doing this is a very good way to understand people. Even their bad actions make a lot more sense if you delve into some developmental psychology along with just engaging your intuition about what their inner 4 year old wants out of life.
On a negative note, I think most people convince themselves of being much more grown up than they actually are. Really it's far easier to just get meaner and more calloused to survive while suffocating the core self. Maturity is more like a deliberate and careful edifice built with a lot of work, self-reflection, and self-forgiveness. It's not a given that just getting older does that, other than the inhibitory part of the brain getting better at restraining the emotional part after adolescence. (Usually, unless trauma happens that's sufficient to get stuck in a particular development stage.)
We are taught in Western and most other societies of today to numb pain. The problem is that we have knowledge of the problems of this world. I think if we allow ourselves to feel the pain of our knowledge and understand our existence through it, we can return to a childlike state and realize the pain is not something wrong with us, but our natural inclination and love for the world telling us that we are doing something wrong.
We may not be able to solve the problems created by our species, but if we learn to live with respect for the planet then we can at least know we are doing as much as we can with our own existence.
> Why can't we just look at each other and imagine the child that person once was
As hard as it is to generalize, I'd say it's because sometimes our needs aren't getting met, particularly our need for safety. When we feel like we're in danger, it's very hard to appreciate wonderful things. ("This person feels like they're in danger" is also a decent way to broadly sympathize with other folks, along the same lines as "imagine the child that person once was.")
Thank you, this is beautiful and deep. I think I will try to imagine people as children and imagine them growing up more. Much easier to project loving-kindness that way.